The Comparison Of The Utilization Of Farmland Terracing And Natural Plot In Karst Valley Area Of Chongqing

The karst region in southwest China is "the world's largest karst continuous belt", mainly distributed in guizhou center for DianQianGui xiang-e-chuan-qian, karst area comprehensive area of about 50 million km2. In southwest area of China in vulnerable population,a large amount of congregate in karst region's population. So in karst region, serious soil erosion, desertifications. The water and soil loss not only results in karst area was the region more thin layers, and lead to a thin layer of soil nutrient loss, causing soil more poor nutrient elements, loss of surface water and ground water also caused the pollution. Cognizant of karst area under the different land USES in karst area characteristics of soil and water loss through controlling soil and water loss and provide scientific basis for rocky desertification control. The treatment technology and experience not only to solve ecological fragile karst area of chongqing environmental governance has important guiding role in southwest karst region, and has the extensive applicability and popularize value.Karst rocky desertification caused a series of environmental problems, research on karst rocky desertification is the hotspot of contemporary international geological research.In this study, summarize the progress of study about Karst at home and abroad. According to the characteristics of karst in Chongqing, builded standard runoff plots in the MuDu river basin of nanchuan area as a research, in two monsoon rains observations, studied the soil erosion under six kinds of land uses. Analysis karst rocky desertification influence on farmland terracing in karst valley area,and then analysis the comparison of the utilization of farmland terracing and natural plot.The conclusion is as follows:(1) Analysis the soil erosion of runoff plots in this study, results showed as follows:Rainfall in the same conditions, the Different methods of land use showed a clear trend:Slope farmland> natural plot> simple engineering measures land> farmland terracing> the woodland> honeysuckle land. Adjustment of the planting structure and certain engineering measures can be very good reduce soil erosion; Year by year, farmland terracing and honeysuckle runoff plots prevent soil erosion effect is getting better and better.(2) There is a positive correlation that sediment loss increases with the increase of rainfall; Sediment erosion appear until the rainfall up to a certain value (12.7-13.4mm),and verify the results of erosive rainfall standard (Times rainfall=12.7 mm) proposed in USLE and RUSLE according to rainfall size. But the regression analysis unable to reflect the time interval of rainfall and the soil water saturation, and can't explain the fact that the smaller rainfall produce larger siol loss. This is the regression equation problems which need to be improved.(3) There is a distribution feature alternate with limestone and sandstone in Karst valley area.It's soil compare with other karst area show some differences——there's a lot of sandstone weathering in the soil of the Karst valley area, The soil structure was improved, soil productivity high,so the residents didn't want to Use the engineering measures for descrtification prevention and control soil erosion.Therefore, taking effective biological measures, complementary with simple engineering measures, and the soil fertilizer, improving the land productivity, according with the characteristic of the natural plots in Karst valley area appears very important.(4) Land use of Karst valley area produced will always exist two ways——farmland terracing and natural plot.For farmland terracing, there are some limited, and construction standards corresponding also higher. At present, farmland terracing is the largest investment in the engineering measure to control soil erosion.Because of this, the capital obviously deficiencies only on state aid but district can afford.Therefore, according to the construction requirements of farmland terracing in Karst valley area, Improve investment criteria of farmland terracing and choose appropriate area which of low Rocky desertification degree and larger top layer thickness. But in the area of high rocky desertification degree and shallow top layer thickness, farmland terracing cannot satisfy crop growth, so we have to consider needed for surface turns the soil, and the source of overburden soil and transportation will become anather problem.Control and research the rocky desertification is still in the initial stage. We need a comprehensive further investigation about the karst rocky desertification, ascertaining rocky desertification status, classifing and proposing the countermeasures to prevention the rocky desertification. Rocky desertification governance is a complicated system engineering, is both a ecological construction project, and also an important project for poverty alleviation, is influenced by natural factors and the social factors, both national interests, and directly related to the fundamental interests of the masses, is a prominent economic problem and a big political problem. Karst rocky desertification, the study and governance, needs a large number of researchers continue to explorate.